Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Fix damaged shark fin antenna
I managed to rip off part of the shark fin antenna housing on my 2013 D4 in a parking garage. GPS and radio still work and I temporarily patched it with duct tape. I got a quote to replace it, but I'm loath to pull down the headliner to do the fix. Are there any alternatives that would involve sealing the hole? I don't care about the looks but want it to be weather-tight. Thanks.
13th Jan 2023 5:59 pm
JDB
Member Since: 25 Mar 2010
Location: NW Hampshire
Posts: 2486
Dry it out and fill with black silicone sealant/mastic if it all still works, unless you are 8ft tall nobody will see it!
13th Jan 2023 6:13 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
The GPS is in the rear tailgate, below the high-level brake light, IIRC the NA spec. vehicles only have a sirius antenna in there, there used to be a mobile phone antenna in therte as well but it was deleted at some point. As you have the pan roof version, you can change the antenna relatively easily - provided the 5 point security Torx haven't corroded into the brass inserts in the base plate mounted on the glass....
It's a self-contained unit so won't leak into the vehicle as the wiring grommet is seperate from the housing and is itself bonded to the metal roof, as above, pump it full of black mastic sealant then get creative with a modelling knife to trim the profile.
Last edited by Flatlander on 13th Jan 2023 6:23 pm. Edited 1 time in total
13th Jan 2023 6:20 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
I agree - don't care about how it looks - just want to make sure water can't get in. Thank you for your suggestion.
13th Jan 2023 6:21 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Flatlander wrote:
The GPS is in the rear tailgate, below the high-level brake light, IIRC the NA spec. vehicles only have a sirius antenna in there, there used to be a mobile phone antenna in therte as well but it was deleted at some point. As you have the pan roof version, you can change the antenna relatively easily - provided the 5 point security Torx haven't corroded into the brass inserts in the base plate mounted on the glass....
Are you saying it can be replaced without removing the headliner? I will have to grab a ladder and try to see what you're talking about. Thanks.
13th Jan 2023 6:23 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
Yes & no... the antenna is mounted externally but the wiring passes through a grommet that is bonded to the metal, it's quite easy to release enough of the headlining to access the connectors, just take off the 'D' pillar trims with the speakers in them, they're on plastic trim clips.
If you take off the rear cover that's held on with the two screws you can see, there's a further two screws that hold the antenna housing to the mounting frame bonded to the roof, you'll see the hard rubber grommet that passes into the car under the rear trim that you removed at first.
BTW, you don't need a ladder, just open both tailgates, then close the top part to give a good working platform...
13th Jan 2023 6:31 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Super helpful - thanks. I still need to decide whether to seal or replace. I don't use the sat radio, so I guess the antenna is non functional. I wish I could just put a flat plate instead as it would allow me more clearance in garages.
13th Jan 2023 6:34 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
On the other hand, it's a relatively cheap early warning device preventing damage to the roof or tailgate....
13th Jan 2023 6:46 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Agree - the crunch of plastic is a good alarm and reminder of my carelessness.
13th Jan 2023 6:50 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
If I don't use Sirius Radio couldn't I replace the damaged part without removing the headliner? Can I cut the wire on the damaged unit and replace it with a used, but intact, part and not attach the wire? Then it's non-functional but cosmetically indistinguishable? Excuse me if I'm way off. Thanks.
13th Jan 2023 7:45 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
Yep you could do that easily - just snip the wires where they enter the big rubber grommet, put some sealant on the ends of the wires to stop capillary action allowing water into the wiring.
BUT
First make sure you can remove the set screws, as previously mentioned, the brass inserts in the mounting frame have a habit of corroding onto the screws...
13th Jan 2023 7:54 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Just to be clear, the rubber grommet is not attached to the antenna, or can be separated, right? I can leave the old grommet on and just attach the new antenna without a new grommet and without attaching the wire? Thanks again.
13th Jan 2023 9:35 pm
Sylvester19
Member Since: 17 Jul 2020
Location: Central Scotland
Posts: 132
I had drill out bolts and replace the brass inserts, the grommet was leaking, some clear silicon around the outside stopped it. As mentioned open both tailgates and close upper one, bottom one is a good platform & no risk of ladder slipping damaging bodywork!
I only removed rear trim panel for access to grommet to check for the leak.
This is my post with photo's replacing brass inserts
Member Since: 20 Jul 2015
Location: Here
Posts: 575
horatio8 wrote:
Just to be clear, the rubber grommet is not attached to the antenna, or can be separated, right? I can leave the old grommet on and just attach the new antenna without a new grommet and without attaching the wire? Thanks again.
This is the best image I can find on a quick search, you can see the 10-15mm of coax from the antenna to the round grommet (the bit with the yellow adhesive protection ring)
Click image to enlarge
13th Jan 2023 10:07 pm
horatio8
Member Since: 09 Apr 2010
Location: Boston, MA
Posts: 22
Flatlander wrote:
Yep you could do that easily - just snip the wires where they enter the big rubber grommet, put some sealant on the ends of the wires to stop capillary action allowing water into the wiring.
BUT
First make sure you can remove the set screws, as previously mentioned, the brass inserts in the mounting frame have a habit of corroding onto the screws...
Halfway through the job I can see you're quite right...the brass inserts are hopelessly corroded onto the screws. I will need to find new inserts or just silicone the new antenna onto the bracket. Thanks again for your help.
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